Thanks a ton for your reply ! Yes, using Quartz ticks is probably the closest substitute to a continuous (float) delay based on a quantized marker. At least, it is predictable.
Actually, the reason why I’m looking for a continuous delay instead of discrete one is that I’m trying to use Quartz to produce audible heartbeats (kind of a ‘bip-bop’ sound) as two consecutive but separate sounds (‘bip’ followed by ‘bop’). What I’m trying to achieve is to always cue the first sound (‘bip’) at the beginning of a bar, and the second one (‘bop’) at a variable delay after that, depending on the number of bpm . For example, in a 4/4 bar at 60 bpm, ‘bip’ would play on beat 1 and ‘bop’ on beat 2, followed by 2 silent beats (bip-bop-silent-silent). But at say 120 bpm, ‘bip’ would still play on beat 1, but ‘bop’ would play closer to the middle of the bar, around beat 3 (bip-silent-bop-silent). Sadly, this is not as simple as adjusting the number of bpm.
In the screenshot below, I’m using a 1-beat bar, and keyboard keys (PageUp and PageDown) to adjust directly the delay in ticks for cueing the second sound. In that context, at 60 bpm, Quartz only has 8 ticks per second to offer, which seems rather limited. This leads to noticeable jumps when moving ‘bop’ from tick 3 (one-fourth of the bar) to tick 5 (middle of the bar). This is where a continuous delay would prove really useful.
Any other solution I’ve come up with was depending on the number of FPS, which is not acceptable considering the regularity of heartbeats. Maybe I’m overlooking some Quartz functionalities?